第8章 基本UDP套接字编程

#include "../Gnet.h"

void do_client(int udpfd, struct sockaddr* pserver_addr, socklen_t server_addr_len)
{
    char buf[MAX_LINE];
    int nread;

    while(fgets(buf, MAX_LINE, stdin) != NULL)
    {
        sendto(udpfd, buf, strlen(buf), 0, pserver_addr, server_addr_len);
        nread = recvfrom(udpfd, buf, MAX_LINE, 0, NULL, NULL);
        fputs(buf, stdout);
    }
}

int main(int argc, const char* argv[])
{
    int udpfd;
    struct sockaddr_in server_addr;

    if(argc < 2)
        perr_exit("usage : client <IPaddress>");

    udpfd = Socket(AF_INET, SOCK_DGRAM, 0);
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(SERVER_PORT);
    inet_pton(AF_INET, argv[1], &server_addr.sin_addr);

    do_client(udpfd, (struct sockaddr*)&server_addr, sizeof(server_addr));

    return 0;
}

#include "../Gnet.h"

void do_client(int udpfd, struct sockaddr* pserver_addr, socklen_t server_addr_len)
{
    char buf[MAX_LINE];
    char reply_ip[INET_ADDRSTRLEN];
    int nread;
    struct sockaddr_in reply_addr;
    socklen_t reply_addr_len;

    reply_addr_len = server_addr_len;
    while(fgets(buf, MAX_LINE, stdin) != NULL)
    {
        sendto(udpfd, buf, strlen(buf), 0, pserver_addr, server_addr_len);
        nread = recvfrom(udpfd, buf, MAX_LINE, 0, (struct sockaddr*)&reply_addr, &reply_addr_len);
        if(reply_addr_len != server_addr_len ||
           memcmp(&reply_addr, pserver_addr, reply_addr_len) != 0)
        {
            inet_ntop(AF_INET, &reply_addr, reply_ip, INET_ADDRSTRLEN);
            printf("reply from %s (ignored)\n", reply_ip);
            continue;
        }
        fputs(buf, stdout);
    }
}

int main(int argc, const char* argv[])
{
    int udpfd;
    struct sockaddr_in server_addr;

    if(argc < 2)
        perr_exit("usage : client <IPaddress>");

    udpfd = Socket(AF_INET, SOCK_DGRAM, 0);
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(SERVER_PORT);
    inet_pton(AF_INET, argv[1], &server_addr.sin_addr);

    do_client(udpfd, (struct sockaddr*)&server_addr, sizeof(server_addr));

    return 0;
}

#include "../Gnet.h"

void do_client(int udpfd, struct sockaddr* pserver_addr, socklen_t server_addr_len)
{
    char buf[MAX_LINE];
    int nread;

    Connect(udpfd, pserver_addr, server_addr_len);
    while(fgets(buf, MAX_LINE, stdin) != NULL)
    {
        Write(udpfd, buf, strlen(buf));
        nread = Read(udpfd, buf, MAX_LINE);
        
        fputs(buf, stdout);
    }
}

int main(int argc, const char* argv[])
{
    int udpfd;
    struct sockaddr_in server_addr;

    if(argc < 2)
        perr_exit("usage : client <IPaddress>");

    udpfd = Socket(AF_INET, SOCK_DGRAM, 0);
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(SERVER_PORT);
    inet_pton(AF_INET, argv[1], &server_addr.sin_addr);

    do_client(udpfd, (struct sockaddr*)&server_addr, sizeof(server_addr));

    return 0;
}

#include "../Gnet.h"

void do_server(int udpfd)
{
    ssize_t nread;
    char buf[MAX_LINE];
    struct sockaddr_in client_addr;
    socklen_t client_addr_len;

    while(1)
    {
        client_addr_len = sizeof(client_addr);
        nread = recvfrom(udpfd, buf, MAX_LINE, 0, (struct sockaddr*)&client_addr, &client_addr_len);
        sendto(udpfd, buf, nread, 0, (struct sockaddr*)&client_addr, client_addr_len);
    }
}

int main(int argc, const char* argv[])
{
    int udpfd;
    struct sockaddr_in server_addr;

    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    server_addr.sin_port = htons(SERVER_PORT);

    udpfd = Socket(AF_INET, SOCK_DGRAM, 0);
    Bind(udpfd, (const struct sockaddr*)&server_addr, sizeof(server_addr));
    printf("waiting for connecting.\n");

    do_server(udpfd);

    return 0;
}

#include "../Gnet.h"

void do_server(int connfd)
{
    ssize_t nread;
    char buf[MAX_LINE];

    while((nread = Read(connfd, buf, MAX_LINE)) > 0)
        Write(connfd, buf, nread);
}

void sig_child(int signo)
{
    pid_t pid;
    int stat;

    printf("in sig_child.\n");
    while((pid = waitpid(-1,&stat, WNOHANG)) > 0)
        printf("child %d terminated\n", pid);
    printf("out sig_child.\n");
}

int main(int argc, const char* argv[])
{
    int lfd, connfd;
    int udpfd;
    struct sockaddr_in server_addr, client_addr;
    socklen_t client_addr_len;
    pid_t child_id;
    const int on = 1;
    fd_set rset;
    int maxfd;
    int nready;
    int nread;
    char buf[MAX_LINE];

    struct sigaction sigaction_set, sigaction_get;
    sigaction_set.sa_handler = sig_child;
    sigemptyset(&sigaction_set.sa_mask);
    sigaction_set.sa_flags = 0;
    if(sigaction(SIGCHLD, &sigaction_set, &sigaction_get) <0)
        printf("sigaction(SIGCHLD) error!\n");

    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    server_addr.sin_port = htons(SERVER_PORT);

    lfd = Socket(AF_INET, SOCK_STREAM, 0);
    setsockopt(lfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));//端口复用
    Bind(lfd, (const struct sockaddr*)&server_addr, sizeof(server_addr));
    Listen(lfd, LISTENQ);

    udpfd = Socket(AF_INET, SOCK_DGRAM, 0);
    Bind(udpfd, (struct sockaddr*)&server_addr, sizeof(server_addr));
    printf("waiting for connecting.\n");

    maxfd = lfd > udpfd ? lfd : udpfd;
    FD_ZERO(&rset);
    while(1)
    {
        FD_SET(lfd, &rset);
        FD_SET(udpfd, &rset);

        if((nready = select(maxfd+1, &rset, NULL, NULL, NULL)) < 0)
        {
            if(errno == EINTR)
                continue;
            else
                perr_exit("select error");
        }

        if(FD_ISSET(lfd, &rset))
        {
            client_addr_len = sizeof(client_addr);
            connfd = Accept(lfd, (struct sockaddr*)&client_addr, &client_addr_len);
            if((child_id = fork()) == 0)//子进程
            {
                Close(lfd);
                do_server(connfd);
                Close(connfd);
                exit(0);
            }
            else//父进程
            {
                printf("child %d connected\n", child_id);
                Close(connfd);
            }
        }

        if(FD_ISSET(udpfd, &rset))
        {
            client_addr_len = sizeof(client_addr);
            nread = recvfrom(udpfd, buf, MAX_LINE, 0, (struct sockaddr*)&client_addr, &client_addr_len);
            sendto(udpfd, buf, nread, 0, (struct sockaddr*)&client_addr, client_addr_len);
        }
    }

    return 0;
}